This invention relates to an occlusion device for the closure of physical apertures, such as vascular or septal apertures. More specifically, this invention relates to an occlusion device that self-centers across a defect and can be retrieved and redeployed in situ.
The heart is generally comprised of four chambers: the left and right atrium and the left and right ventricle. Separating the left and right sides of the heart are two walls, or septa. The wall between the two atria is the interatrial septum, and the wall between the two ventricles is the interventricular septum. There are several defects which can affect the septa of both children and adults, including patent ductus arteriosus, patent foramen ovale, atrial septal defects (ASDs), and ventricular septal defects (VSDs). Although the causes and physical characteristics of these defects vary by type, these defects may generally comprise an aperture, flap, or hole in the septum which allows blood to shunt between chambers in the heart where there is no blood flow in a normal, healthy heart. This abnormal blood flow can cause a variety of health problems.
Normally, permanently repairing certain cardiac defects in adults and children requires open heart surgery, which is a risky, painful, and expensive procedure. Surgically closing an aperture in the heart requires the patient to undergo general anesthesia and requires opening of the chest cavity. The patient may spend several days in the hospital and may take several weeks to recover before being able to return to normal levels of activity.
To avoid the risks and discomfort associated with open heart surgery, modern occlusion devices have been developed that are small, implantable devices capable of being delivered to the heart through a catheter. Rather than surgery, a catheter inserted into a major blood vessel, and an occlusion device is moved through the catheter to the treatment site where it can then be deployed at the defect. This procedure is performed in a cardiac cathlab, and avoids the risks, pain, and long recovery associated with open heart surgery.
There are currently several types of occlusion devices capable of being inserted via a catheter including, button devices, collapsible umbrella-like structures, and plug-like devices. These modern occlusion devices can repair a wide range of cardiac defects, including patent foramen ovale, patent ductus arteriosus, atrial septal defects, ventricular septal defects, and may occlude other cardiac and non-cardiac apertures.
One form of occlusion device generally has a first side, a second side, and a center section. Once the occluder is deployed, the first side is positioned on one side of the aperture to be occluded, and the second side sits in the other side of the aperture. The occluder's center section extends through the center of the defect or aperture being occluded. The left and right sides occlude the aperture on the respective sides of the aperture. Because the center section of the occlusion device may be small relative to the size of the aperture to be occluded, it is a challenge to ensure the occlusion device is properly centered across the aperture.
Further, the size of defects varies from patient to patient, with some defects being larger than others. If the defect is large, it is desired that the center section of the occluder remain in the center of the defect so that the first and second sides of the occluder are optimally positioned to occlude the entire defect. If the center section not optimally centered, the first and second sides of the occluder may not be optimally placed so that the defect is properly occluded. If the defect is not properly occluded, blood may continue to shunt through the defect lessening the effectiveness of the occluder.
Many occluders are designed so that the first and second sides are collapsible, allowing the occluder to fit inside a catheter. When in the collapsed position, it is desired that the occluder be highly compact so that the smallest diameter catheter may be used when deploying the occluder. A catheter with a smaller diameter reduces trauma, improves maneuverability, and allows the device to be used in patients who have small vasculature or who are very young. Loading the device into a small diameter catheter must be done by hand, requires a high degree of manual dexterity, and can be time consuming.
Once the device is loaded, it is maneuvered through the catheter to the treatment site within the body, where it is then deployed. In the event the device is not optimally deployed, it may be retrieved, and the procedure may be performed again. While some types of occlusion devices are retrievable via catheter, many require open heart surgery to be retrieved.
Even in instances where the device can be retrieved using a catheter, retrieval may require insertion of a larger diameter catheter than that used for insertion. A larger diameter catheter may be required because the device may not readily resume the compact shape it had before deployment. Once retrieved, the device may be compromised from the stress of withdrawing it back into the catheter, even if a larger diameter catheter has been used. As such, it may not be possible to reuse the retrieved occlusion device.
In addition, devices retrieved via catheter are typically not properly loaded for redeployment. Thus, even if the device is retrievable, the device must be pulled back through the catheter and be completely removed from the catheter so that it can be properly reloaded. Reloading is time consuming, additional time to the procedure, and creates wear and tear on the device. Often, the retrieved device cannot be reused because it has been damaged by the retrieval process. If the device cannot be reused, a new device is required, which increases the cost of the procedure.
Thus, there is a need in the art for an occlusion device that is easily loaded into a catheter, and that can be retrieved, reloaded, and redeployed in situ. There is also a need in the art for an occlusion device which has a centering system to improve the ability of the device to be centered in the defect.